>In VFP6 project, I have made a couple of minor amendments to a form. i.e. adding a button, and a new page within a page frame. I checked page numbering etc, before saving.
>
>Now when trying to launch the form to do more work, I get the following message:
>"Expression evaluated to an illegal value". I have tried Refreshing, and Clean up project, but to no avail.
>
>Has anyone got any suggestions, or do I go back to my last back up?
>
>Thanks, Pete

Pete,
Hard to debug situation. Highly probable error stems from a control's property setting. ie: A grid's minimum rowheight is 19. A setting of any value between 0-18 (not -1) would raise the error.
I'd first try this :
-Launch the class browser and open the form (set file type to form)
-Click 'view code' and copy code
If you can get to this point it's easier to quickly check properties in code.
If class browser cannot open it too then try :

use yourformname.scx
browse for !empty(properties)

And check properties. You might fix there if you find one that'd generate the error. Close and open the form as usual. Good luck
Cetin